1. Technical Field
This invention relates to the field of solar energy collection, and more specifically, to a solar collector pipe.
2. Background Art
With the increasing cost of conventional fuel and energy for heating and cooling, much attention has been directed to the possibility of the use of sunlight as a source of energy for heating. Assorted solar water heating systems have previously been provided. For example, some conventional solar water heating systems involve a box which uses a transparent glass plate as a top surface of the box. Inside the box, a plurality of round black PVC pipes are placed in a snake-like pattern, back and forth through the box. Other conventional solar water heating systems involve a water-containing, round, black tube heated by solar radiation in the center of a space defined by a solar energy collector.
Both of these types of conventional solar water heating systems are placed in a location exposed to the sun, such as on the roof of a home, and water pipes, such as for a back-yard pool, are attached to either end of the round pipe network. When the sun shines down through the glass on the top of the box or through the solar energy collector, heat energy is absorbed by the black pipes inside the box or collector. The heat energy is then transmitted to the water flowing inside the pipes, thereby eventually heating the water.
These conventional solar water heating systems, however, have certain drawbacks. Conventional systems are inefficient in energy collection. That is, they do not collect and transfer solar energy efficiently and directly to the water. Thus, whatever form the solar energy absorbing element may take (e.g. black, water-containing tube), it is inherently inefficient and is continually losing a significant portion of the absorbed energy by the well known mechanisms of convection, conduction and radiation. The interaction of these heat loss mechanisms limits both the amount of energy transmitted by the absorber to the internal adjacent fluid and the peak temperature attainable by that fluid.
Conventional systems are also expensive to manufacture and difficult to install, requiring a substantial amount of labor on-site during installation, thereby resulting in a system which is difficult and expensive to maintain. For example, conventional pipe and box systems are inordinately large (i.e. 12 ft.xc3x9724 ft.xc3x978 in.), often covering significant portions of the structure being heated, and are expensive (i.e. $6000-$10,000). The size of the box presents a variety of problems. A significant amount of space must be provided to house such components. Furthermore, since such components are generally relatively heavy, the supporting structure must often be strengthened in some way to accommodate the excess weight of the components involved.
In an effort to overcome these size disadvantages, other types of solar energy collector systems have been developed which attempt to eliminate the need for large flat pipe and box systems of the type previously described. These solar energy collector systems, however, while often reduced in size, generally involve a combination of dissimilar structural elements which are often costly and complex. This also leads to many of the disadvantages previously described in conjunction with the large flat pipe and box systems.
Therefore, it would be advantageous in the art to have a highly efficient solar collector which is easy to manufacture and assemble, is easy to maintain and repair, and is structured of inexpensive materials, thereby overcoming the aforementioned disadvantages of conventional solar heating systems. Embodiments of the present invention solve these problems through a solar collector pipe that directly conveys fluid to be heated and collects and transfers solar energy efficiently and directly to the internal fluid, thereby maximizing both the amount of energy transmitted to the internal fluid and the peak temperature attainable by that fluid.
In association with an embodiment of present invention, a solar collector pipe includes a transparent portion for admitting solar energy into the solar collector pipe. Internal to the solar collector pipe is an absorbing portion for absorbing solar energy. A conduit portion is also included and comprises a reflecting surface thereon for reflecting solar energy received through the transparent portion onto the absorbing portion. The transparent portion, the conduit portion, and the absorbing portion together define at least one fluid passageway for conveying the fluid.
Accordingly, the solar collector pipe of this invention has many advantages, one of which is that it is highly efficient. That is, by providing a transparent portion and a conduit portion (with an internal reflecting surface) with certain shapes, such as parabolic shapes, solar energy is appropriately directed to the absorbing portion, particularly if it is located along a vertical center axis of the solar collector pipe. Thus, fluid within the solar collector pipe may be heated directly by the solar energy transmitted through the transparent portion, as well as by reflected energy from the reflecting surface of the conduit portion and through heat transfer from the heat absorbing portion. Additionally, the solar collector pipe of the present invention is relatively inexpensive and easy to manufacture, assemble, maintain, and repair.
In particular embodiments of the invention, the fluid within the solar collector pipe is carried within a conduit inside the solar collector pipe which is integral with the heat absorbing portion of the pipe rather than being carried by the reflecting portion of the pipe. In this way, the reflected heat energy from the larger solar collector pipe area may be focussed on a smaller amount of water, and the heat may be efficiently transferred thereto. In other embodiments of the invention, the internal conduit is carried between two heat absorptive parts of the solar collector pipe and held together with an appropriately shaped clamp. Endcaps, connectors and securing brackets similar to those described in reference to other embodiments of the invention may also be used.
The foregoing and other features and advantages of the present invention will be apparent to those of ordinary skill in the art from the following more particular description of the invention, as illustrated in the accompanying drawings.